With future exploration of macrophage properties in mind, we established a
novel cell line (HS-P) from a transplantable histiocytic sarcoma, derived o
riginally from a tumour in an aged F344 rat. HS-P was subjected to 70 seria
l passages, in which the mean doubling time was 15.7 h. The cells, which we
re round, oval or polygonal in shape, were arranged in a compact sheet. The
y reacted to varying degrees for lysosomal enzymes (acid phosphatase and no
n-specific esterase) and with the following antibodies: ED1/ED2 (rat macoph
age/histiocyte-specific), OX6 (rat MHC class II-specific), lysozyme antibod
y and alpha1-antichymotrypsin antibody. Electron microscopically, HS-P cell
s showed lysosomes and prominent cell projections. These findings indicated
that the cultured cells were macrophage-like. Syngeneic rats inoculated su
bcutaneously or intraperitoneally with HS-P cells invariably developed sarc
omatous tumours consisting of monomorphic mononuclear cells, which exhibite
d cytochemical properties similar to those of cultured HS-P cells. Bioassay
and reverse transcription-polymerase chain reaction methods revealed that
tumour necrosis factor-alpha increased on addition of lipopolysaccharide (L
PS), indicating that HS-P cells remained LPS-responsive. HS-P cells may pro
ve to be a useful tool for in-vitro studies of macrophage function. (C) 200
1 Harcourt Publishers Ltd.